1. Field of the Invention
The invention relates to a paper coating slip comprising                at least one inorganic pigment and, based on 100 parts by weight of the inorganic pigments,        less than 40 parts by weight of organic polymers and        less than 25 parts by weight of water or other solvents having a boiling point below 150° C. at 1 bar.        
In particular, the invention also relates to the above paper coating slips in which a binder is bound to the inorganic pigment (referred to below as pigment-polymer hybrid).
2. Description of the Related Art
Paper coating slips usually comprise pigments, organic binders and water.
Water or other solvents are required only for the coating process itself. They permit uniform distribution of pigment and polymer on the paper to be coated.
Anhydrous paper coating slips have the advantage of lower weight. Transport costs can be reduced.
In addition, energy costs are also saved since no drying is required after the coating.
WO 01/00712 and WO 01/00713 disclose anhydrous paper coating slips which comprise organic polymers as pigments (organic pigments for short).
Such organic pigments are expensive and are obtainable only by complicated preparation processes. Anhydrous paper coating slips which need not comprise any organic pigments are therefore desired.
WO 93/12183 discloses a process for the preparation of composite polymer-pigment particles. The polymer adheres to the pigment surface.
Pigment-polymer hybrids and processes for the preparation thereof are disclosed in patent application FR 04 07 806 from Omya (date of application Jul. 13, 2004).